Abstract
A large amount of wastewater is directly discharged into water bodies without treatment, causing surface water contamination. A rotating biological contactor (RBC) is an attached biological wastewater treatment process that offers a low energy footprint. However, its unstable removal efficiency makes it less popular. This study optimized operating parameters in RBC combined with external membrane filtration (RBC-ME), in which the latter acted as a post-treatment step to stabilize the biological performance. Response surface methodology (RSM) was employed to optimize the biological and filtration performance by exploiting three parameters, namely disk rotation, hydraulic retention time (HRT), and sludge retention time (SRT). Results show that the RBC-ME exhibited superior biological treatment capacity and higher effluent quality compared to stand-alone RBC. It attained 87.9 ± 3.2% of chemical oxygen demand, 45.2 ± 0.7% total nitrogen, 97.9 ± 0.1% turbidity, and 98.9 ± 1.1% ammonia removals. The RSM showed a good agreement between the model and the experimental data. The maximum permeability of 144.6 L/m2 h bar could be achieved under the optimum parameters of 36.1 rpm disk rotation, 18 h HRT, and 14.9 d SRT. This work demonstrated the effective use of statistical modeling to enhance RBC-ME system performance to obtain a sustainable and energy-efficient condition.
Highlights
IntroductionBecause of the increase in the volume and the pollution level of wastewater, the treatment costs increase
Colloidal particles and dissolved nutrients can pass through the membrane pores, unless an additional layer of biofilm grows on the membrane surface, which aid in biodegradation, as often occurs in a membrane bioreactor [35]
The results described that 64% decolorized wastewater was obtained with glucose as a carbon source, while a maximum removal of 83% was obtained with 10 g/L glucose, and a maximum chemical oxygen demand (COD) removal efficiency of 73% was obtained
Summary
Because of the increase in the volume and the pollution level of wastewater, the treatment costs increase. Various treatment methods employed for wastewater treatment are ozonation, photocatalytic oxidation, and biological processes. The treatment of water with ozone has a wide range of applications, as it is efficient for disinfection as well as for the degradation of organic and inorganic pollutants. Photocatalytic oxidation is a very powerful air purification technology and has the ability to destroy particles as small as 0.001 microns (nanometer). Photocatalytic oxidation technology possesses several advantages, including environmental protection, the complete degradation of pollutants, and no secondary pollution. Biological methods have been widely adapted in wastewater treatment with the advantages of being more cost-efficient, having more minor footprint requirements, higher specific biomass activities, and being sustainable and environmental-friendly [3,4]
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